14 Apr 2014

PY2OHH's Pititico 10 parts transceiver for 40m

Andy Cutland has sent me this link. It is from, Miguel,  PY2OHH's excellent site which is full of ideas for QRP and QRPp enthusiasts. I can thoroughly recommend it for ideas.  I would expect this RX to hear signals, but be quite deaf as there is no audio gain apart from that in Q1.

Apparently the headphones were around 500 ohms impedance. I guess a crystal earpiece might work as audio is derived across R2. Maybe then C5 could be deleted?

Q1 must act as a (crystal controlled) regenerative detector on RX with the level of oscillation set by R2. Not sure of RX-TX shift as this will depend on RX and TX current. There is no low pass filter either, as shown. This means harmonics will also be detected and emitted. Still, this is meant to be VERY simple. I must try it.
http://4.bp.blogspot.com/-TlNqb0N-7V0/U0SFVljBTjI/AAAAAAAAUkY/xbyhirCu7AU/s1600/pititico.gif

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2 comments:

  1. py2ohh miguelWed Apr 23, 11:01:00 pm GMT+1

    hello Roger

    I use a earphone from a commom telephone abot 500R of Z.
    For adjust RX-TX shift you need to change C2 and C4 ... be care with the current it easy goes to 100mA and may damage the transistor or xtal...

    73 from Brasil py2ohh miguel

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  2. prem chnad kMon Aug 24, 05:21:00 am GMT+1

    what is the transister used . whether we can use a vfo for receiving other frequency can it be used as a walkie talkie for short distance by two units this is vu2rpc from india

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